abstract class Element{
  def contents:Array[String]
  def width: Int = if(height==0)0elsecontents(0).length
  def height: Int = contents.length
  def above(that: Element): Element =
      new ArrayElement(this.contents ++ that.contents)
  def beside(that: Element): Element=
              new ArrayElement(
                 for(
                   (line1, line2)<-this.contents zip that.contents
                ) yield line1+line2
              )
  override def toString = contents mkString "n"
}